scholarly journals Testing Mechanical Properties of Rock Bolt under Different Supports Using Fiber Bragg Grating Technology

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4098 ◽  
Author(s):  
Guo ◽  
Wang ◽  
Ma ◽  
Wang
Keyword(s):  
Fiber Bragg Grating ◽  
Axial Force ◽  
Applied Load ◽  
Bragg Grating ◽  
Change Rate ◽  
Active Loading ◽  
Loading Mode ◽  
Force Mechanism ◽  
Loading Modes ◽  
Prestressed Anchor

: Fiber Bragg grating (FBG) sensors, which can accurately measure strain, can be integrated with rock bolts with small fingerprints. In this paper, according to the force mechanism of prestressed anchor and non-prestressed anchor, different loading modes were designed, named active loading mode and passive loading mode. Then, FBG technology was used to monitor the axial force variation of prestressed anchor and non-prestressed anchor in different loading modes. Based on the test results, it is found that when the anchoring force is relatively small (<35 kN), prestressed anchors need to be tested by active loading mode, and non-prestressed anchors need to be tested by passive loading mode. For the prestressed anchor, the force condition of the bolt-shaft was similar to that of the two-force bar, and the axial force of the bolt-shaft was nearly the same along its entire length. Taking the applied load as the reference, the change rate of the axial force of the bolt-shaft was less than 10%. For non-prestressed anchor, due to the plate, there is a certain area surrounding the plate where the axial force of the bolt-shaft was greatly influenced. With applied loads of less than 15 kN, the change rate of the axial force on FBG1 was greater than 10%. With applied loads of greater than 20 kN, this was less than 10%. In this area, influenced by the plate, the axial force of the bolt-shaft increases, and as the applied load of the pullout test increases, the influence decreases.

Test on Axial Force of Double-Walled Mode Pipe Pile Based on Fiber Bragg Grating

2018 ◽  
Vol 55 (11) ◽  
pp. 110605
Author(s):  
王永洪 Wang Yonghong ◽  
刘俊伟 Liu Junwei ◽  
张明义 Zhang Mingyi ◽  
张春巍 Zhang Chunwei ◽  
王明明 Wang Mingming ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Axial Force ◽  
Bragg Grating ◽  
Pipe Pile

scholarly journals Fiber Bragg Grating Monitoring of Full-bolt Axial Force of the Bolt in the Deep Strong Mining Roadway

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4242
Author(s):  
Peng Wang ◽  
Nong Zhang ◽  
Jiaguang Kan ◽  
Zhengzheng Xie ◽  
Qun Wei ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Axial Force ◽  
Growth Zone ◽  
Bragg Grating ◽  
Fiber Grating ◽  
Monitoring Method ◽  
Mining Depth ◽  
Working Face ◽  
Before And After ◽  
Mine Roadway

With the increase of mining depth and strength, the evolution of bolt axial force is increasingly becoming important for ensuring the reliability and safety of support. To improve the problem of the existing coal mine roadway pressure-monitoring method, whereby it is difficult to continuously monitor the axial force of the bolt over a long period of time, a full rod fiber bragg grating (FBG) force-measuring bolt and system were designed based on the principle of fiber grating sensing. It was found that a trapezoidal groove is a relatively better groove. The linearity between the center wavelength offset of the fiber grating and the axial force was more than 0.99, and the conversion formula between the axial force of the bolt rod and the wavelength change of the fiber grating were obtained. The real-time monitoring revealed that the axial force of the bolt obviously changed before and after compression. The axial force distribution curve can be divided into the stable zone, growth zone, and peak zone. The influence of the roadway abutment pressure was approximately 130 m ahead of the working face, and the peak area was within the 25–35 m range of the advance working face. The axial force of the bolt rod at the end of the anchorage linearly increased with the tail end of the bolt, the axial force of the free segment was the largest, and the overall stress was essentially the same. The application results demonstrate the feasibility and effectiveness of the FBG full-length force bolt.

scholarly journals Strain Conditions Monitoring on Corroded Prestressed Steel Strands in Beams Based on Fiber Bragg Grating Sensors

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2288
Author(s):  
Guo-Xi Fan ◽  
Fan-Tong Lin ◽  
Peng Li ◽  
Ji-Gang Han ◽  
Huai-Shuai Shang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fiber Bragg Grating ◽  
Residual Strain ◽  
Fatigue Performance ◽  
Bragg Grating ◽  
Loading Mode ◽  
Steel Strand ◽  
Fbg Sensors ◽  
Corrosion Of Steel

Fiber Bragg Grating (FBG) sensors, with excellent properties, have been widely adopted to monitor the mechanical parameters in civil engineering in recent years. On the other hand, the current study on fatigue performance of corroded prestressed steel strands is still limited, and this is mainly because the long-term strain conditions monitoring is difficult to conduct. Based on the aforementioned considerations, a total of six beam specimens were fabricated in this study. The loading mode of four points bending was adopted in the form of sinusoidal waves in the experiments. On basis of the experimental results, it can be concluded that the fatigue life of the beam decreases sharply with the increase of the corrosion rate of steel strands. Besides, with the increase of the maximum fatigue load, the fatigue life of the beam will decrease significantly. Furthermore, the existing fatigue damage of steel strand inside the beam before corrosion may further accelerate its fatigue failure. As a result, the fatigue life of the beam is reduced because of the stress concentration. Under the same external load, the strain increment and the residual strain of steel strands in the stages of loading and unloading after corrosion increase significantly compared with other stages, while the existing residual strain always shows an increasing trend at various static loading stages. Therefore, the corrosion of steel strand seriously affects not only its mechanical properties, but also its fatigue performance. Finally, the FBG sensors are capable of measuring the steel strand strain, as well as the long-term strain conditions.

scholarly journals A Fiber Bragg Grating Sensing Structure for the Design, Simulation and Stress Strain Monitoring of Human Puncture Surgery

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3066
Author(s):  
Pengwen Xiong ◽  
Xin Huang ◽  
Yulong Li ◽  
Peter X. Liu
Keyword(s):  
Fiber Bragg Grating ◽  
Axial Force ◽  
Simulation Analysis ◽  
Bragg Grating ◽  
Average Sensitivity ◽  
Bragg Wavelength ◽  
Determination Coefficient ◽  
New Type ◽  
The Difference ◽  
Force Calibration

In order to improve the precision and stability of puncture surgical operations to assist doctors in completing fine manipulation, a new of type puncturing needle sensor is proposed based on a fiber Bragg grating (FBG). Compared with the traditional puncture needle sensor, the new type of puncturing needle sensor is able to sense not only the axial force, but also the torque force during the puncture process. A spoke-type structure is designed near the needle tip. In order to eliminate the influence of temperature and realize temperature compensation, a reference fiber method using three FBGs is applied. FBG1 and the reference FBG2 are pasted on the upper and lower surfaces of the new-type elastic beam, and FBG3 is pasted into the groove on the surface of the new type of puncturing needle cylinder. The difference of Bragg wavelength between FBG1 and the reference FBG2 is calibrated with the torque force, while the difference between the Bragg wavelength of the FBG3 and the reference FBG2 is calibrated with the axial force. Through simulation and sensing tests, when the torque force calibration range is 10 mN·m, the torque average sensitivity is 22.8 pm/mN·m, and the determination coefficient R2 is 0.99992, with a hysteresis error YH and repetition error YR of 0.03%FS and 0.81%FS, respectively. When the axial force calibration rang is 5 N, the axial force average sensitivity is 0.089 nm/N, and the determination coefficient R2 is 0.9997, with hysteresis error YH and repetition error YR of 0.014%FS and 0.11%FS, respectively. The axial force resolution and torque resolution of the new type of puncturing needle sensor are 0.03 N and 0.8 mN·m, respectively. The experimental data and simulation analysis show that the proposed new type of puncturing needle sensor has good practicability and versatility.

scholarly journals Experimental Strain Measurement Approach Using Fiber Bragg Grating Sensors for Monitoring of Railway Switches and Crossings

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3639
Author(s):  
Abdelfateh Kerrouche ◽  
Taoufik Najeh ◽  
Pablo Jaen-Sola
Keyword(s):  
Fiber Bragg Grating ◽  
Experimental Tests ◽  
Cost Effective ◽  
Measuring Method ◽  
Bragg Grating ◽  
Railway Network ◽  
System Failures ◽  
Railway Infrastructure ◽  
Train Speed ◽  
And Control

Railway infrastructure plays a major role in providing the most cost-effective way to transport freight and passengers. The increase in train speed, traffic growth, heavier axles, and harsh environments make railway assets susceptible to degradation and failure. Railway switches and crossings (S&C) are a key element in any railway network, providing flexible traffic for trains to switch between tracks (through or turnout direction). S&C systems have complex structures, with many components, such as crossing parts, frogs, switchblades, and point machines. Many technologies (e.g., electrical, mechanical, and electronic devices) are used to operate and control S&C. These S&C systems are subject to failures and malfunctions that can cause delays, traffic disruptions, and even deadly accidents. Suitable field-based monitoring techniques to deal with fault detection in railway S&C systems are sought after. Wear is the major cause of S&C system failures. A novel measuring method to monitor excessive wear on the frog, as part of S&C, based on fiber Bragg grating (FBG) optical fiber sensors, is discussed in this paper. The developed solution is based on FBG sensors measuring the strain profile of the frog of S&C to determine wear size. A numerical model of a 3D prototype was developed through the finite element method, to define loading testing conditions, as well as for comparison with experimental tests. The sensors were examined under periodic and controlled loading tests. Results of this pilot study, based on simulation and laboratory tests, have shown a correlation for the static load. It was shown that the results of the experimental and the numerical studies were in good agreement.

A Fiber Bragg Grating acceleration sensor with temperature compensation

Optik ◽  
2021 ◽  
pp. 166993
Author(s):  
Xianfeng Zhao ◽  
Zhen’an Jia ◽  
Wei Fan ◽  
Wangfei Liu ◽  
Hong Gao ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Temperature Compensation ◽  
Bragg Grating ◽  
Acceleration Sensor
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